jack, Thank you for your nice comment - I could take those all day.😊 I got onto YT to pass on what I have learnt over many years, if you and others find that useful then I am well pleased … Martin

How to do iron casting?

Walter, Thank you for your loverly comment. I too watch way too many YT videos - and my wife keeps telling me so 😊Waste of time she says. But I too sub to very few. I suppose I should at least sub to more of those I watch regularly but they all seem to have so many subs that one more would not help much. I guess I am more than a little jealous of their success! Sadly, my health makes it very hard to make new videos. I still intend to try as I have many, many ideas that need showing. But years of shoveling sand and humping moulds around has destroyed my back and even just standing up is now an exercise in how much pain can one bear - old age is a crock of crap!.......Martin

Jim, You do me great honour sir - much more than I think I deserve. Such praise is deserved only by those who are much better than a lowly metallurgist and foundry man such as myself. Over the years I have had the pleasure of watching some people at work who in one way or another put me to shame - old timers with moulding skills to die for and new technologists with an eye on quality at reasonable cost. I have recently seen complicated 10 Kg aluminium castings in 357 alloy, thick and thin sections all over the place and when machined the metal looks just like wrought billet in soundness and excellentness of finish . I would I had the equipment to do this, or the skill of those old timers. It is my wish to pass on some of what I have learnt and if I am managing to do that then I am indeed happy. I guess its a bit like another YTer (pooroldchap) said "When an old person dies its like a library burning down and all I am trying to do is save a few books". If I personally manage to save a few pages of a few books I will be happy. I go started on YT because I saw a lot of bad info and I felt (perhaps a bit conceitedly) that it had to be counteracted, in truth I doubt I will ever succeed in this as the bad has a big head start but I will keep at it. However I see little point in taking my efforts to the point of trash talk against an individual (regardless of how wrong I think they are) I would rather lead by example by showing what I believe to be the right techniques and by explaining why they are right. Sometimes this does involve stating why other techniques are wrong and I will always try and do this on a non personal basis. Sadly many people have got off on the wrong foot by reading books etc that are part of what John Campbell calls the 6000 year old technology that infests the foundry industry. His work and publications are very much a breath of fresh air in the foundry industry, his "Castings Practice The 10 Rules of castings" should be mandatory reading for all budding foundry men before they are allowed to pick up a box of matches to light the furnace. My only slight criticism of this book is that it is in some parts a little heavy for the non metallurgist. I wish that I could cover some of those other areas that you mention but sadly I lack the experience and I suspect that good up to date information on things like investment casting is not going to be easy to come by as the investment industry has always been secretive (a local investment foundry on realising who I was would not let me past the front door lest I "steal" any of their supposed secrets). Campbell though has some interesting insights. I might finish by saying that I know what aluminum is just as you know what aluminium is, I work in both inch and metric systems although to be honest I am pretty much all centigrade now. I see no point in pedantic petty "discussions" over regional differences in terminology as long as we have a tolerably workable understanding of what each of us is on about its all good. Oh, and I dare not slag off the "yanks'" grandfather was born in MT (dad in BC Canada) the male line goes back to 1677 in MD and the female line to 1632 in MA so I sorta am a yank! Once again thank you for your fine comment, it made my day... Martin

yes sir, well stated, and thank you for the advice on John Campbell; i will try to get that book: Casting Practice, The 10 Rules of Casting. Thanks again, very much.

Jim, If you are up for a heavier type of read John Campbell's "Complete Casting Handbook" is the go. It contains the "Ten rules" plus another 900 pages of wonderful information. But be warned it is in places quite a heavy read - I struggle with some of it....Martin

Awesome... I'll try to get a copy of that... thanks again

You're the conversations I never got to have with my great-grandad. He was a tool and die maker all his adult life, and the way my father speaks of him, he was just like you. Calm, kind, willing to take time and show instead of just tell. He'd have my dad, aunts and uncles over, and part of playing outside was coming into the shop and helping out while he made a new toy for them to play with. His wrench is still in my office, and I remember cutting sprue off plastic models using a pair of side cutters he made himself. I may never be a die maker, but I've considered going back to school to become an engineer so I can do the kinds of work my ancestors did, and you're almost inspirational really. The attention to detail that's so frequently missing in society can't be missed in an environment such as where you work, and it brings me hope that a career change would be a good choice.

Mohd, I think that one can only learn the subtle nuances of any process by doing or, but perhaps to a lesser extent, by closely watching and studying an experienced practitioner. There is just so much in depth nitty gritty little stuff that no engineering school would ever have a course long enough to include it all. I hope that I have helped you and thanks for the comment.... Martin

Raspy, Since then I have improved my sound recording. The word was "better". Drier sands ram easier and tighter giving a closer surface on the mould and hence a better surface finish on the casting. Sands on the damp side are much tougher and the mould tends to breakaway less particularly on the part line edges but damp sand rams looser i.e. with larger holes between the grains so the finish is rougher. I juggle the sand moisture level according to the demands of the job, but note that the "juggling" is only slight... Martin

@@olfoundryman8418 Awesome. Reply is very much appreciated. Audio really wasn't even that bad back then. I heard everything very clearly except that one word. So then would it make sense that slightly more dry sand would need more venting? And wetter sand would need slightly less venting since there is more space between sand particles?

Bill, Thank you for saying that - I wish more people would appreciate it though 😏… Martin

Ted, Thanks for watching - we Aussies are a pretty easy lot to please 😊 but if you really want to watch something fascinating try this kzfaq.info/get/bejne/fatnhKRiyM65qqs.html well worth the effort if you are into old time skills....Martin

Flatcat, I am reminded here of a fellow foundryman who started out with green sand but decided that it was just too difficult to make moulds from unless one trained and practiced for many years. He went over to fenotec hard sand and commented that any monkey can make a mould from it, whereas real skill is needed with green sand. Now I have never used a hard sand - apart from silicate CO2 - and now never will because as you say the messing with resin catalyst etc is a bit much unless you have one of those continuous mixers that commercial foundries use. So perhaps you need to be aware that green sand is just not that easy. Good luck with it and if I have helped then I am well pleased.... Martin

Ashkira, Sounds like you are on the right track although I would have thought 5% possibly a bit low 7.5% or even 10% are commonly used but it does depend on the sand a lot with fine sands requiring more than coarse. It does sound as though with anything higher you would get a sand so strong as to be difficult to use.... Martin

Ma61 - Not really all that secret 😏 just a lot of dirty dusty work. It is what gives me the good finish, although sometimes I wonder if its worth the effort...Martin

Olfoundryman Don’t sell yourself short! Anyone can cast a rough, porous casting but those of us who are a bit more “OCD” really appreciate someone taking the time to show them the absolute best possible practice for the best results, and I’ve never seen better results than yours.

ma61, In truth I am a bit short of "best possible practices" and as I learn more I change to the new and better. Looking back just a few years I have for example improved the pouring basin that I use by adopting John Campbells recommendations. My degassing is better too. But this is a never ending saga, there is always a better way - we just have to find it 😊. The time that I take is my pleasure and all the more enjoyable for the appreciation that others show for it... Martin

Thomas, As always giving the time is my pleasure, I am glad that you liked the video.

Glad that you like it, Sharing is my pleasure. Just watched your CO2 videos - I liked them - Love the cannon.

Clarke, Nice to hear from you again. Yes, it took me a while to think of it too! The idea of using a crushed aggregate as a moulding material is hardly intuitive - the thought that using an angular as against rounded grain might restrict flow-ability during mould ramming is ever present. Initially I placated that thought by reasoning that the grinding process that I use might tend to produce a sort of rounded grain as its action is to roll the particles being ground, it is after all how they "grind" balls for bearings. But then I remembered that the steel industry often uses sands based on olivine, chromite, or zircon. While the last is often an alluvial product and therefore more or less rounded the first two are crushed products and I understand work quite well as moulding materials. Indeed my first moulding "sand" was crushed quartz obtained from a defunct gold mine, it worked. Be aware though that there is a price to pay for this use of very fine facing sands - their constant addition to the bulk sand slowly reduces permeability of the sand. I need to be thorough with venting my moulds and things like lettering on plaques can round out (rather than take a sharp impression) as steam pressure prevents proper filling of fine details - for larger plaques I oven dry the moulds to prevent this. Eventually though one needs to throw out much of the sand and add new in to restore permeability.Those adjusting nuts under the fixed grindstone are backed right off - the stone actually floats on the sand being ground. Also you can use the grinder to size you back up sand by adjusting the nuts up to lift the fixed stone and quickly running all the (dried) backup sand through the machine. At this setting 500 litres of and will go through in under a couple of hours. I guess that you could do this too for any washed sand that you can obtain that might be a bit on the coarse side. Also I have in mind to buy some zircon sand and grind it into a facing material as an expansion defect preventative on difficult jobs. I draw you attention to Barry Manilowa's comment below - his idea is well worth consideration.

Henry, You are lucky! Most people here are in lockdown.... Martin

Robert , I am glad you found it useful.... Martin

Michael, Keep playing, but remember its an acquired art learnt through lots of practice and study......Martin

Michael, My pleasure, I hope that the information proves useful for you.

Contriver., Aussie TV narrator -hmm - which one? Aussie sure but my voice is to loud and harshly aggressive to be a TV narrator - nice thought though they get paid a motza..😊… Martin

Michael. I am glad that you und it informative - that's what I try for... Martin

Gez, Thank you for your comment - bless Presso whoever he is - do know him by another avatar? Yep, definitely a Melbournian,eastern suburbs, are you close? I wish a few more would discover my channel 😀… Martin

Mate yes pretty close inner east - I can't believe you're running such a fantastic operation in a garage - your techniques seem far more professional than a lot of these other blokes - I'm only starting up - extensive machining and woodworking workshop but want to start casting bits and pieces - just really good to see this level of local skill - you need to train up an apprentice. I am trying to watch all your vids .

Gez, First thing get lots of drop sheets to cover all your machines, foundry seems to generate lots of abrasive dust that you need to keep off your good machines. Are you offering to be an (unpaid 😀) apprentice?.. Martin

Too old to be an apprentice but I'd happily be a foundry labourer - pretty good with shovel - and I could get the hang of being a crucible assistant - however don't want to upset your missus - she seems to be very good with those pours.

Jimmy, To be honest good sand is hard to get anywhere! If I measure my sand with a micrometre it has a maximum size of 0.15mm. Remember this is the maximum size of any sand grain in my sand most of the grains are a lot smaller. From what you are saying your sand may in part at least be a lot coarser than this and while many people do use sands quite a bit coarser I would not to use a sand much coarser than 0.25 mm as the casting finish will be quite rough. Unfortunately it is very difficult and very slow to sieve sands down to this size. For mixing in the bentonite I just spread the sand thinly on a concrete floor add the required amount of bentonite evenly on top of the dry sand and work it in with a garden rake. When it seems to be mixed fairly well I begin to add the water as a fine spray a little at a time and raking all the while, occasionally I stop raking and shovel it into a heap and then rake it out flat again. As the sand gets wetter it should swell and when it seems to feel about right (like a garden soil ready to put seeds in) shovel it into a heap and cover it with plastic sheet or place it in a big plastic barrel or a rubbish tin. I would start with about 7.5% bentonite but how much you will actually need will depend on your particular sand. Don't get it too strong as its very hard to work with if you do and don't get it too wet as that also makes it hard to work with and perhaps a little dangerous too. Just worry about getting a good easy to use sand at this stage - one that holds together well has good edge retention and seems to ram to a reasonable finish against the pattern - worry about the best finish possible later... Martin

@@olfoundryman8418 I did mix up about 30 liters of sand it seemed to clump up kinda bad. I had originally mixed about 15 liters of very fine silica sand and i got it too wet. It got muddy. So I cut it with some sifted river sand and that made it too course. So I added a bit more bentonite and it helped. But it made little balls and now I need to grind it up. I watched your video and I need to make some sort of mixer thrasher like yours and run it through it.

Jimmy, I think you will be impressed by how much better the sand feels and works after going through something like my aerator. Getting the moisture content right is a bit of an acquired art - just keep at it - you will get there... Martin

Mark, Beach sand is usually way to coarse. Most foundry sands come from wind blown dune deposits and these tend to be much finer sand. In addition beach sand unless well washed will contain salt and I don't thing that is too good an idea. Also it often contains bits of shell, you can check for this by adding a some vinegar to a little of the sand if it fizzes than you have shell present. You might get away with a little shell with aluminium casting but probably not with copper base and definitely not with cast iron. You might do better going to your local hardware store and seeing if they have any children's play sand some that I recently saw is, while not as fine as I use, way finer than a typical beach sand. Also sometimes paving sand i.e. the sort of sand they sweep between just laid pavers is quite fine hardware shops have this too. (But check both of these for shell particles) I know that somewhere near Noosa but inland a bit I think is a deposit of glass making sand and I have been told that it is quite fine. Unfortunately it is not possible to separate out the facing sand once a mould has been made and used so yes it does build up in the backing sand and this is eventually a problem as such fine sand reduces the permeability to a point where the sand becomes just about useless and I have to throw the lot out and replace it from my steadily depleting stock of new sand! You may notice in my videos that I often vent my moulds a lot a necessity with such fine sands. If you can find someone near you who makes resin coated sand, they use reasonably fine sands for this and they will probably be prepared to sell you some of this sand before they resin coat it, it is mainly the one grain size and for a good moulding sand a range of sizes gives better mould strength but you could just up the clay a bit to compensate But in answer to your question the grinding should work on beach sand and strangely perhaps it does not seem to matter that the sand after grinding is now broken pieces rather than semi rounded grains It is a pain of a process to do though and do wear a respirator silicosis is nasty! Note that it is possible to set the grinding machine so that it will just grind the sand a little rather than reduce it to almost flour like I do... Martin

Thanks Martin for your very detailed and prompt reply. I did add some children's play sand to my stock of beach sand a while ago when I had a few castings to do at the same time. I think I can get bulk supplies of that really white paving sand from our local landscape supplier. I think I am going to dump my current sand and make some new stuff based on your comments. I am really impressed with the surface finish you are able to get on your castings though. Thanks again. Mark Presling

Johnny, The expansion I mentioned is the result of the sand changing its crystalline structure. The change that bothers us aluminium casters occurs at around 570 Deg C. (there are other volume changes at higher temperatures, 870 and 1470 Deg C). This is very much a surface effect and while it may mar the surface of a casting I think it unlikely to produce major dimensional problems. Things like core shift are more likely due to sloppy foundry practices - probably badly sized core prints in this case., or just not quite right pattern equipment. One might think that they would have discovered the problem during production but I guess they never overbored the cylinders😏. When you are pushing the limits with something like this its a bit of a matter of luck - Years ago we bored a Rover 6 out by 0.209" (yes! nearly 1/4 of an inch!) to take standard land rover pistons as they were very cheap - who wants standard pistons.😊 The first block split on boring but the second was OK and ran for many miles since. Checking the bores for wall thickness if it can be done accurately enough does impress me as a sensible precaution, but resleeve may be indeed the more certain way... Martin

@@olfoundryman8418 Many thanks Martin for such a detailed and interesting reply ! Regards, John

Terry, Thank you for your comment and the subscription. The resin coated sand that I use comes pre-coated with the resin, I do not add it. The heat of the mould that I pour the resin coated sand into first melts and then cures the resin thus bonding the sand. This resin coated sand is widely available and is quite cheap. A cup saucer and spoon, Wow, not an easy thing to cast! I have seen photos of something like this done using lost foam but it was pretty rough (as is most lost foam work!) I guess that it could be done with investment casting but unfortunately this is not something that I do.

brandt, My pleasure.... Martin

Mark, Again than you for your comment. This is a difficult area of foundry work to address - it is so variable sand to sand and even job to job it really comes into the category of "touchy feely", something difficult to convey in a video. But I know from remembering my "Newbie" days that it is of great concern to the novice moulder. I well remember struggling with the questions of how wet and how to process. Fortunately and perhaps surprisingly one can be quite a bit less than "spot on" and still have success. I can only express the hope that those looking to learn will gain something from the video. Foundry work certainly is an area where the preparation involved in the logical flow of the process is most necessary. There is a progression of steps and each must be done for the next to be able to occur.Incidentally I would value and suggestions that you might have for future videos. I have one coming soon on my degassing lance.

Safe Work Practice in the Home Foundry would make for a very good video, Work Flow, PPE, and the like. A basic primer series on Pattern Making for Home Casting, discussion of pattern draft, ; Flask sizing, Flask lift and how to prevent it, the Fluid Dynamics of Molten Metal in a casting, metal turbulence, debris inclusion/prevention, metal chill, Shrinkage and how to deal with it in the Home Foundry. These are just some of the ideas I have come up with.

Wow! That's quite a list - well - I asked for it I guess! I have printed it out and added it to my "to do" folder. Not sure I am the right person to do a safety thing as I am not exactly that safe myself - but maybe I can come up with a few reasonable guidelines, This is an area where it varies from a typical Indian iron foundry where they tote hand ladles of iron around wearing nothing but a pair of shorts and in bare feet (life is cheap in India I guess) all the way to two fools I saw in a video the other day so suited up in head to toe safety garb as to look like spacemen - they could not see what they were doing and could not get out of their own, let alone each others, way, falling over their own garb as they were. I guess some lawyer told them to wear it all! (Let me know if you want the video links to the above examples.) I have a good friend who is a pattern maker so maybe I can prevail upon him for input in that regard. (I might add that 3D printing is not the universal answer that many think when it comes to pattern making, and nor in my opinion is expendable foam.) I have contemplated a video on flasks at least with respect to my "flask journey" and my current thoughts. Fluid dynamics etc. gets into the whole subject of gating - this is immense! But I will give some thought to what I could say on it in 20 minute or perhaps a few 20 minute episodes - many (most) and including professional foundries get this so wrong that something certainly needs saying - I fear fierce and vitriolic argument by the entrenched luddites though. Degassing generally (I have an upcoming video on my lance) is an area ripe for a good video as there are many techniques (some totally insane) out there that border on the farcically counterproductive and are born of a complete lack of basic chemistry, thermodynamics, and any understanding at all of what is required to successfully degas - again I fear the attack of the luddites. Shrinkage is something that most commercial foundries have under control, backyarders will need to improve their techniques when they learn to get gas levels down as currently (judging by what I have seen on YT) it is only the gas content of their castings that fights shrinkage so indeed something could be said there.Then I guess there is the area of metal selection (cans are lovely metal but a casting No-No) and how and what it is melted in. There is a lot that could be said and pointed out here and some surprisingly easy solutions - but again the luddites will arm themselves! (pitch forks and wooden faggots for the "at the stake" burning because of my "heretical views" Stay tuned it could be fun!

Mark, I don't know why but my reply has appeared with a line through most of it. The line should not be there, read around/through it - sorry

Hi Martin, the line through your reply made for interesting reading, not sure just how you managed that one. I didn't realise the green sand casting community was filled with so many old school Luddites wanting to burn heretics at the stake for daring to have different views. Never mind, talk is cheap and actions speak louder than words, and someone mentioned something about a pen and a sword doing battle. [JOKE] I was only suggesting some topics, you dont have to rush out and do all of the topics, just the ones that interest you. As for Safety, I think that you work safely enough to have not hurt yourself all these years, but I was mostly thinking about how you lay out your work during a casting so you are not risking tripping while using the full crucible filled with molten aluminium. Like you I have seen some people on YT doing some really stupid stuff or not wearing enough protection while casting aluminium and other metals. Hot metal is no joke and I suspect that molten metal would be somewhat akin to napalm in the way it would stick to clothing or [shudder] bare skin, with the resulting burns being deep and intense. Almost warrants a Mythbusters type of investigative video series.

Ray, Sadly, no I am not referring to yellow brickies sand. I am aware that a "Fat" brickies sand does contain some clay I believe that's what makes it "Fat" or workable rather than feeling harsh or coarse. However I doubt that it would have enough clay to provide a strong enough bond to make moulds with, for that you would have to add clay, usually bentonite. But unfortunately any brickies sand that I have seen is way too coarse for sand casting , doesn't mean that you can't use it but the castings will have a very rough finish. There used to be a lot of sand quarries along Centre Road, I got my first sand from one of these in 1968 but it was already worked out even then. My last lot of sand came from a quarry either on the Frankston Dandenong road or the Dandenong Hastings road can't quite remember it was a long time ago. The Lilydale railway line goes through two sand deposits that might be suitable one is just on the Melbourne end of Box Hill station the other the cutting just before Camberwell station - it gives them no end of trouble with erosion! Don't know how you would get at either of these! I believe that there is a quarry somewhere further east from where I got my last sand that MAY have a suitable sand. When your exploration gets a little closer to actually casting send me a PM I may be able to offer some assistance if you live near by - I am in the eastern suburbs of Melbourne Thank you for the subscription.

@@olfoundryman8418 Hello Sir! I'm looking into trying to find the perfect sand around my area (Mid West, US) I was wanting to know if there is anything I should look out for, As I'm not sure about the different sand types in my area vs yours, Is there something, I should be looking for in sand? a grit number, or something to make figuring out a type of sand a little easier, Sorry, this is all new to me and I'm not sure how to use proper terminology . Thanks! look forward to hearing from you, Have a good day!

@@HORSEDICKoMPEG, Firstly what sort of sand are you looking for? - A natural sand ready to use straight out of the ground like mine, or just plain washed sand to which you can add bentonite clay too, or it doesn't matter either will do? Depending on your answer I may have some ideas for you. But getting a good moulding sand is always a problem and I think that is why so many hobbyist casters just get some petrobaond sand - problem is it is expensive and needs more maintenance than does a green sand but it can produce a nice finish and does appear a bit more forgiving that green sand... Martin

@@olfoundryman8418 Thank you for the response, I'm pretty new, So I'm not sure which sand would work best, I have a few criteria. I'd like something that is pretty cost effective, Can be easily sourced, and in decent amounts, and gives a good finish. and of course the easier the better. but I'm not opposed to mixing bentonite and sand if I have too. I'm just not sure where to get natural sand locally. but Ideally that would be the best, Finding a local natural sand that I may only need to grind down (Like for your facing sand). I've looked into petrobaond and it seems like a good starting point. I'm just not really sure on the amounts, Is a 30 Lb bag a decent amount, or id imagine I would need some more (Depending on how much I cast and size) I guess really the only answer to that question would be to start casting. (Waiting on all my supplies) Thank you again for the help!

David, Don't worry about be a rookie - we all were once - just get out there and give it a go (how hard can it be 😊) I have never tried casting aluminium onto/into wood but I suspect that the wood will give off a lot of gas which may make for an "interesting" casting, I suggest that you get the wood as dry as possible. The original form of lost foam used a normal green sand rammed carefully around an uncoated foam pattern and I know of local foundries doing much the same as this using fenotec hard sand. A more modern version of lost foam does indeed use a coat on the foam, the coated foam is placed into loose sand (no binder) usually with the help of vibration and the metal poured onto the foam. The coat is quite thin (less than 0.5 mm) and must be porous to allow the gas from the decomposing foam to escape out into the sand. The idea is that the gases do NOT come out through the metal but instead go out through the sand. I have tried to develop a suitable coat but so far I am not happy with the results achieved although they show some promise. My coat was based on clay as a binder and fairly fine refractory particles including some talc. Plaster of Paris is not suitable. The difficulty is in getting the coat thin, uncracked when it dries, and porous. Companies like Foseco do make coatings for just this purpose. Also some people seem to manage to just put the uncoated foam into loose sand and pour the metal in - amazingly it seems to work... Martin

Gaye, The sieve in the thumbnail for this video is quite fine with about 0.5 mm spacings. The sieves I use when actually making moulds have about 1.6 mm openings. I bought these larger sieves from CMT equipment in Brisbane - they have a web site.... Martin

@@olfoundryman8418 thank you very much

Geoffrey, Lots of people swear that Baby powder (Talc) acts as a release but I do not use it. Instead I use a commercial parting agent - it is fine ground calcium carbonate. There are possible health problems with talc but calcium carbonate is pretty benign. There are quite a few things that can cause sticking - sand too wet, too much clay in sand, ramming to close above the pattern etc. One thing I have found that seems to make patterns stick is having too smooth a finish - It seems counter intuitive I know but its what I have observed. So I paint my patterns with a matt paint to make then slightly rough. I like to have an ever so thin layer of parting agent on this matt paint film. I chose black paint as it shows the white parting agent nicely. Unfortunately the matt paint tends to wear smooth and I usually replace it every 20 to 30 uses of a pattern. Hope this helps.... Martin

@@olfoundryman8418 Thanks very much for your quick reply mach appreciated, I've been watching your video casting the pistons and I'm glad i watched the last part of the video great to see a excellent engineer at work thanks again for your valuable videos,

@@olfoundryman8418 The commercial parting agent seems to have done the trick thank a lot,

Joe, Yes, I suspect that a surfactant would make the water disperse quicker. My choice would simply be a small amount of household dishwashing liquid. I am ignorant about the surfactant properties of NH3 but would not use it as I once had my lungs just stop working when I accidentally breathed in a good glug of NH3 fumes - My chest just froze and I could neither inhale or exhale - a most uncomfortable feeling for the minute or two that it lasted - talk about life flashing before one's eyes! However I have no idea if it would cause any problems with pattern wetting (and hence sticking) or metal mould reactions. It would be a "suck it and see" situation to be tried on a small quantity of sand at first. Interesting thought though.

Olfoundryman Thanks for your reply, I too have had that experience with NH3, I used it when I was restoring clocks, it was great for part cleaning though mixing up the solution with 0.88 (mind has gone blank!) was 'fun' if i had a spillage. I enjoy watching your videos as many others do, keep it up. Regards, J.

Joe, Re 880 NH3 try adding a few crystals of iodine to some and then let the result dry slowly (nothing actually appears to happen but just dry what looks like the original iodine crystals) DON"T make much at once though, no more than 1/4 of a teaspoon, as it is about the most unstable explosive known, we used to spread very small quantities on a dance hall floor while still wet and when it dried it popped and cracked under peoples shoes. Need to keep it in the dark as light slowly decomposes it. Touch powder it was called because all you had to do was touch it and bang it went - Ah - memories! I am no expert here but a bottle of vinegar on hand might be the way to render an ammonia spill a bit safer. How was the ammonia used in clock restoration? I have a couple of friends who are into that and I suspect that they would like to know. I am glad that you enjoy the videos - more are on the way.

Olfoundryman After stripping down the movements I would pop all the parts in a large snap top plastic tub filled with a strong mix of NH3 and warm water, close it up and leave for a few hours (parts must be submerged), Then take each part out and immediately buff up with 0000 steel wool in hot water with lots of washing-up liquid, then I would lay each part out on tissue in a warm oven to dry fairly quickly, Works very well to remove oxidation and crud, If parts are not completely covered there will be deep pitting along the line to air, (lesson learned the hard way!). Iodine eh?. Cheers, J.

Joe, Sorry running a bit behind! Thanks for the info, I will pass it on to my horological friend. Trying to remember my corrosion studies from my metallurgy student days and I am not surprised that you ran into corrosion problems - copper and its alloys are attacked by NH3 and I guess that at the airline the combination of NH3 and Oxygen got stuck right in!Iodine - yep, try it, and enjoy, but be careful!

Charlie, I use the facing sand to achieve the best possible surface finish on my castings. However its use causes problems. Firstly I have to make it and that is a slow dusty job so I try to use as little as possible to make my supplies last. Secondly, it is very fine and thus has low permeability this causes all sorts of problems particularly if the layer of it around the pattern is thick. Thirdly it remains in the sand and thus the backup sand slowly becomes contaminated with this fine material and its permeability eventually becomes unworkably low. At this stage I have to throw it all out and start with a new batch of backup sand. I do not believe that it would be practical to use pure facing sand because of this permeability issue. In addition no sand lasts forever - the clay bond weakens and the sand picks up all sorts of tramp junk that causes strange effects on the surface of the castings. Re play sand I have found some play sands to be badly contaminated with small bits of sea shell, Ok perhaps for aluminium casting but not a good idea for copper base alloys. Check by adding some Hydrochloric acid to a table spoon or two of the sand, if it fizzes then there is shell in the sand, vinegar might do but the HCl is better. I have found one lot of play sand that was not even silica don't know what it was but it was a lot softer than true sand and I would not have liked to try and use it for metal casting. Best hardware store sand I have found is "Paving sand" this is the sand they sweep in between just laid pavers, it is fine and seems to be good quality silica sand it was definitely finer than any play sand I came across but I did note that every time I looked at the local hardware store the sand was different! Cheers back from Melbourne Australia..... Martin

@@olfoundryman8418 Martin, thanks for the detailed reply. I took your advice and have been experimenting quite a bit over the last several weeks. I'm not sure what you use to measure grain size in Aus but I found a local pottery store selling 200 mesh silica that I mixed 10:1 with powdered bentonite. I would certainly describe it as having a "floury" consistency and I believe it should be a close approximation of what you are using in this video. As you predicted, too thick a layer of the stuff and all the hot gas comes sputtering back up the sprue so I have been using it in combination with my original mix as a backing sand. The difference in surface quality is night and day compared to what I was achieving before. I do think my facing sand could use a bit more clay because smaller details will occasionally break loose on me with patterns that had no trouble in the courser sand, but I guess that only makes sense given the greater surface area of the fine sand. I intend to test this theory once I finish building my muller, as I'm not too keen on mixing a batch by hand again. Aside from that I am quite pleased with the results. I haven't observed any defects that would indicate the presence of shell, but perhaps I just got lucky with the hardware store sand. I do suspect that the clay bonds are beginning to weaken though. I had assumed that one could simply add more clay but I hadn't considered foreign materials getting mixed in over time so probably best to ditch it when necessary. I will be having a look at paver sand when that time comes. Anyway, I still have plenty more to learn about casting so always looking forward to your new videos!

Life, You are not wrong - quite a few heart breaks but they were all learning experiences... Martin

Matt, Wood flour is simply the dust that you get from wood when you sand it. It is/was added to moulding sand to help stop expansion defects that come from the sudden expansion of silica sand at about 500 deg C. This expansion can produce surface defects known as "rat tails", "scabs", or "buckles". Foundry supply houses used to sell wood flour, however these days many have unfortunately stopped doing so. You could try making your own by sanding some (soft) on a disc sander and catching the dust with a vacuum cleaner with a new bag in it, after a few pieces of wood you should have a bag full of wood flour. Also if you can find any woodworking shops near you they might have a dust extraction system full of wood flour.... Martin

Achelon, Sands are a problem! You need a fine - sand most that you will come across are way to course. My san is a natural sand ready for use straight form the ground with maybe a little sieving to remove the odd pebble it naturally contains the binding clay. You might try a paving sand - this is the sand that they sweep into the joints of just laid pavers it is usually available at hard wear stores, just be sure that it does not contain little bits of shell. You could ask any local foundries where they get their sand. You could ask any local resin coated sand manufactures if they will sell you sand before it is coated just get the fines that they have. You could ask a geology teacher from a local senior school or university if they know of any local sand deposits - have they a geological map of the area - study it for any sand deposits. Go to google and look for sand suppliers locally have they a local quarry go visit and tell them you want the finest sand they have. Use google earth to spot quarries and match this info with the local phone book. I can for example see several sand quarries near to the now defunct one that my sand came from. The orange/yellow colour of exposed sand is a dead give away on google earth...good luck … Martin

@@olfoundryman8418 Thanks, I have a place in mind that I will start testing :)

Sorry ​@Olfoundryman forgot to tag you.

Jarlenfos, I generally do not advise people to make up ultra fine facing sands because it slowly builds up in the system sand and destroys its permeability. Because of this I have to make frequent use of a vent wire to allow steam to escape from the sand. I have got used to this but even so it does cause me problems that mean that eventually I have to throw all my sand out and start anew. The facing sand that I make up is indeed quite fine and it does contain a lot of "flour" but it is nowhere near all "flour" my grinding process lets a lot of small grains through. If the material you have is all silica flour i.e. all less than 300 mesh then I would be very dubious of using it on its own as a facing material. You could try adding it, say, 50:50 to some of your base sand and trying that as a facing material (need to add some bentonite too, maybe at 5 - 7% of the silica flour addition) - be prepared though for possible problems of steam coming out through the metal rather than the sand (the metal in the feeders will tremble). Misruns through air unable to get out through the sand fast enough in some areas are also possible. Its a "suck it and see" sort of thing - Good luck.... Martin

Nataliya, Thank you for your comment and the subscription, I appreciate them both. Your English is a lot better than my Ukrainian! All of my videos used to have subtitles. However due to changes made by KZfaq any subtitle added after uploading to YT no longer appears on the video. I now add all my subtitles before uploading so there should be subtitles on my later videos. I may do as a friend has done with his videos and that is to upload the videos that subtitles have been removed from by YT a second time but only after adding new subtitles as they are then part of the video and can't be removed. I am happy to answer any questions that you might have.... Martin

meditative, The lower rotating disc is made from aluminium but has two thickness of an abrasive cutoff wheel (9 inch diameter) glued to its top surface. The upper and stationary disc is an old grindstone of about 9 inch diameter 1.5 inch thick with a 2 inch hole in the middle through which the sand passes.... Martin

Vlad, I have replied via email.... Martin

@@olfoundryman8418 👍

aubreyaub, I guess it looks a lot like "brickies loam" but it is much, much finer. It is a natural fine sand deposit that contains about 15 to 20% of some natural clay... Martin

@@olfoundryman8418 Thanks mate. Interesting.

K, When I started out petrobaond was unheard of so I had no choice but to go with green sand. I managed to obtain about 1/3 of a cubic yard of a very good greensand from a worked out quarry. Unfortunately it ran out and I had to get more (about 8 cubic yards this time) from another quarry its what I am using now but it is not as good as the first sand.. Most foundry sands are wind blow dune sands that have somehow got infiltrated with a natural clay. About 1/3 of Melbourne is underlain by such sands although not all of it is suitable as most is too coarse. Sands laid down by water are usually too coarse. The term "sharp" does not mean sharp like a knife it just means "clean" i.e. free from clay. The term "fat" is sometimes used to describe a clay bearing sand - ask any bricklayer. Dune sands are rounded to sub-angular, water laid sands tend to be rounder. interestingly many sand substitutes used instead of silica sand are crushed products so they are very angular, chromite and olivine for example but zircon sand is quite rounded having been laid down by water (here in Australia the zircon sand is about 90 AFS). I prefer a rounded to sub- angular shape but obviously my facing sand will contain a lot of broken grains from the grinding and thus eventually so too will the backup sand because each time the facing sand becomes part of the back up for next time. If you are thinking of using that red clay as a binder for your own home made green sand I would suggest that you do not but rather get some bentonite instead -you don't know what bonding properties the red clay will have... Martin

Thank you for the response I have a bag of bentonite from a well drilling company. I bought about 5 years ago. I will give it a go. May do a small batch with red clay/ sand just to test see how it holds up. I am tinker type of fellow. Gets me into trouble sometimes. Do you do any test for strength on new sand before casting with it?

K, Sounds like a plan! Other than grabbing a handful and squeezing it and then breaking the lump in half to see how it breaks, which gives you some idea of how strong it is I do not do any sort of test. Mainly I work from how good a mould it will make - too strong and it won't ram down properly and will have lots of cavities bigger than a sand grain, too weak and it will all break away when you try to get the pattern out particularly around the cavity edges be aware that too much or too little water in the sand do respectively exactly the same thing. I judge the water by how the sand handles, how it rakes, how it sieves how it feels - I guess that after all of these years I just know 😏... Martin

Steve, Yes I have seen people do as you do to mix their sand. One person I know puts a large steel ball (an old cannon ball I think) in the mixer (paddles removed) and this rolls the sand like a muller does. Thanks for sharing... Martin

KW, Yes, my flasks(frames, boxes) are cast from aluminium. I know that many people use wooden flasks and indeed I started out that way, and I still have quite a few wooden boxes which I use - reluctantly - from time to time. It is surprisingly hard to make a good set of flasks out of either wood or metal - the difficulty is in getting them to sit flat on the bench and on each other - they tend to rock unless made on good equipment. I do prefer the aluminium boxes as it is easier to give them the long guide pins like I use, hard to do this on a wooden box. My early aluminium boxes were patiently cast one side at a time in sand - eight castings for a complete box! and with only a few wooden boxes at that stage it took forever to get the over eighty sides that I needed for the 10 boxes that I wanted. Later box sides were cast in a simple gravity die that did allow different side lengths to be cast. This is a much quicker casting process and I was able to cast about 200 sides in a day or two. They were then machined using a milling machine so I was able to get everything the same. I have used these same boxes now for over 20 years and have made thousands of castings in them. I have actually already thought of doing a video about how I made them as well as one about how I made some of my earlier the sand cast ones as I think that their design is the better. As they say "stay tuned"Over the next day or two I will put together a list of where I get my supplies from and than I will post it here as another reply. Yep, I reckon that about 50% (at least) of YTers are from the US. The Ozzie foundry community is out there that's for sure but its very small compared to that in the US

yes I agree, I have mocked up my wooden sides ready for me to cast in aluminium alas they will be small, I will need to do something special myself to make 18inch ones. And thank you for the prompt reply

If you make an episode on making them I think you will have no problems in selling them as well. Even a small amount of cash helps a new YTuber with cameras and mics etc, so if they were affordable it would be something worth doing in my opinion. Also I would strongly recommend putting a Paypal link in your description as many people will be happy to donate or even pay for some items. Just my 2 cents lol

KW, My earlier sand cast boxes were made in such a way that I could expand (and later contract) the size of the box in one or both directions to accommodate an "oversize" casting if needs be. They did not really need to be machined apart from drilling a few bolt and pin holes, although in truth I did eventually face the top and bottom edges as it made them nicer to use but it wasn't strictly necessary. If you can send me a private message with an email address that I can send a few photos to I will take some pics of these boxes because I think their design is well worth considering. PS. Small boxes definitely have their uses too. I have a pet philosophy "never use a box any bigger that it has to be". Always remember that the bigger the box and the older you are they heavier the box is!

Hi guys, I too would be interested in suppliers please Olfoundryman. I'm also from Brisbane and wanting to try my hand a casting but suppliers and info for that matter can be hard to find. There isn't much on the net explaining what to look for when trying to source sands. Composition? Grain? I recently bought some F54 foundry sand off Ebay from someone in Vic but its a lot courser than I thought it would be. So I would really like to find something I can use as facing sand or make one of these machines if need be. But I still need to know what sand to use that is readily available to us here in Se QLD. There is a rather nice fine white sand that come from Stradbroke Island, I know Brickies like it for it colour, but it is a really nice fine grain. Unfortunately I don't know anything about its composition.

M, I am glad that you have enjoyed the videos and thank you for your subscription. To be honest I have never made up my own green sand but I would start with the finest sand I could get and add 7.5 to 10% bentonite with enough water to make it damp like a good garden soil. Rake it, ,shovel it, walk on it, roll it with whatever you have - even drive over it. I will see if I can find a link or two for you.... Martin

@@olfoundryman8418 ok, Martin I will do with these proportions ... thank you very much for your attention

At 6.54 I add about 0.5% by weight of corn flour to the sand. This is to help prevent expansion defects that can occur with silica based moulds because of silica's sudden change in volume by plus 2.5% at around 550 Deg C. This can cause shifts in the mould surface which produces defects in the casting surface. An organic substance like the corn flour can absorb some of this expansion and thus help to avoid the defects. Traditionally wood flour was used but as most of the local foundry supply houses have shut down its getting hard to buy that... Martin

Mekaz, Yes, I am and I usually wear a mask but that makes it a bit hard to ad-lib the video as I shoot it - you would not have heard what I was saying. Much of the dust (but sadly not all) that you see is actually clay not silica and then exposure is only for a short time. But yes it is a concern..... Martin

Leethal, Yes I believe so - Wargrade uses one with a large ball (cannon ball?) rolling around inside it to act like the rollers in a traditional muller... Martin

Wind, All my sand is a natural moulding sand, that is, it is straight out of the ground and naturally contains the right amount of clay binder. And by the term "sand" I mean this natural mixture of silica sand and clay. My facing sand is actually 1/2 my backing sand plus 1/2 new unused sand, I grind this mixture in a sort of home made mill not unlike an old time stone flour mill. I add a small quantity of corn flour (about 1/2%) as an anti expansion defect additive... Martin

meditative, The rotating disc is an aluminum casting that has an 9 inch abrasive wheel glued to it. This wheel needs occasional replacement.... Martin

Dustin, I made them... Martin

Peter, Thank you for your comment. I don't think that I ever took the kids to the beach! We went to the mountains instead. But you are right - I would have found myself searching for the sand that was just right - its a curse! - not too dry, not too wet - but somewhere between the water line and the dunes there would have to be some - wouldn't there? Finding it the right grain size and free from shell, now there is a really big ask :) And then of course beach sand does not have any binder in it (they cheat making those beach side sand sculptures of course) But to get slightly serious it is often not one time beach sands that become natural moulding sand deposits instead it is wind blown dune sands that get infiltrated by clays (possibly from lava flows that once covered the sands and then decomposed) that make the substance so precious to me and lots of other foundry men besides.

Rabih. Using less bentonite means a weaker sand, this will always ram tighter and thus as you say give a better finished mould. I have occasionally used a 0.5 mm opening sieve, and that's close to 40 mesh, for some very fine work but its difficult and slow to get much sand through such a sieve although a weaker sand would go through easier, Normally I use a sieve with 1.5 mm openings. The problem is that a weaker sand makes a weaker mould and you get problems with cavity edge and delicate mould parts breaking away. What is important is the clay to water ratio. If there is too much water the sand will be sticky and not give a good surface. Even a low clay sand if too wet will give a rougher finish that a high clay sand that has the correct amount of water in it. sometimes when I require a very good finish I deliberately use the sand a little on the dry side because it will ram better but if I want a tough sand for difficult work I will use it just a little on the wet side. How well the clay is spread through the sand is very important too. Without a muller of some other sort of mixer like my aerator for instance clay dispersion will not be the best and it may take some uses of newly made up sand for it to develop its full strength.... Martin

nkuku, Many people do not use facing sands at all. Some just use new sand as a facing material as it is stronger and not contaminated with rubbish. The lengths that I go to produce my facing sand are a bit over the top and I do not recommend the procedure to anyone but those determined (like me) to get the best possible surface finish.... Martin

Gene, 40 mesh is way to coarse, that's almost 0.020 inches -the biggest grains in my sand are .006 inch or about 120 to 150 mesh. That's the biggest grains, most are way smaller but admittedly my sand is a bit fine. The washed graded sand that I use to make silicate cores from is about 70 mesh and therefore has a size about half that of your 40 mesh and I think this 70 mesh a bit rough. 40 mesh sounds like concreting sand! Have you tried "paving sand" this is the sand they sweep between pavers after they have been laid the stuff we have locally is quite fine - not fine enough for me but way finer than 40 mesh. The usual amount of bentonite is maybe 10% max many use 7.5% and I have heard of just 5% being used, the coarser the sand the less you need. BUT it does take some time for the bentonite to get worked into the sand properly and for the bentonite to absorb the water properly. You may have to work the sand a bit - ram it into a mould break it out and re-ram a few times and also leave it sitting for a couple of days in a sealed container and then see what it is like. I guess you have to buy the wife a new kitchen blender 😏. If the blade was steel (highly likely) you should be able to pull the flakes out with a magnet but I can't see enough of the steel getting into the sand to contaminate the castings.... Martin

Martin to be honest I was about to get pissed because my sand would not hold shape. I will ck on pacer sand. thx

Gene, Patience my friend, there is a lot to learn in this game and it does take a lot of time to come to grips with it. It was many years before I could regularly produce the sort of result that I get now both with respect to finish and internal soundness. Its all practice... Martin

Martin I found paver sand and it is a very fine grain. I spent the last few days cleaning and sifting out any rubbish. Spread out on plastic to dry. After dry it is white in color. What size screen do you use for facing?

gene, Usually I use a 1.5 mm opening size screen for the facing. However for very special work I sometimes use a screen with a 0.5 mm opening, this is very hard to push the moist sand through and it is thus only suitable when the part is flat and small. I also use a 1.5 mm opening to sieve on the first of the backing sand... Martin

Ron, Its the old story " you just can't get good help these days!" But she who must be obeyed and damn quickly too has offered to loan YOU the window cleaning kit. :).... Martin

Sure thing, IF you include round-trip transportation! It's a long way there from here in Michigan, USA. :-) I've cleaned the odd grimy window in my lifetime, it's not difficult, nor beneath my station.

Ron, Casting is not lucrative enough to run to a trip from Michigan to Melbourne, however if you can find the fare I will put the beer on ice and throw another shrimp on the barbee. The window, incidentally, is on the afternoon sun side and I leave it dirty to stop the hot sun coming in and getting in my eyes as I work, sort of like permanent sun shading, well, that's my story and I am sticking to it :). (The fact that I only make moulds in the morning and therefore do not use the bench in the afternoon is of course completely irrelevant. But maybe 5 minutes with a damp cloth is in order - one day!... Martin PS. If I did have the money The "maid" and I would tour the US and Canada as my family goes back to 1600s arrivals in the US so I have relatives in just about all states and I would love to meet them in person.

Well dang. I guess my ploy to get a free trip to Australia failed. :-D I've been wanting to visit for about 40 years now. If you're up to it, or don't mind dropping hints at your children, perhaps you could make or receive as a gift, a louvered window shade for the outside. That should help with both glare and solar heat gain. :-) I spent nearly 2 years in Cuba when I was in our Marine Corps, and such window coverings weren't an uncommon sight there. You're a brave man (or a fool) for referring to your wife as "the maid". When I said, "the maid", I simply meant whoever cleans the shop.

Ron, 40 years, hell, no wonder that shrimp on the barbee has gone off! I do have inside venetian blinds on the window but never had to use them what with all the dirt (parting agent mainly) on the glass, it is most effective at stopping the glare :) Its just like whiting on glass houses, but I will drop hints as per your suggestion. The good lady and I have an understanding but all the same best you do not mention the term "maid" and my use of it too her.. :) I clean the shop ..... occasionally!... Martin

greg, No, but I should be. In my defence - albeit a weak defence - most of the dust is actually clay not silica and it is of short duration as the added water soon stops it completely. By the way after a lifetime of doing this I am now almost 80 and although I have numerous health issues due to the physicality of a life throwing moulds around, recent checks have shown my lungs to be among the best bits left ,😊 guess I have just been lucky but I do find things like wood dusts from sanding etc. much more annoying then what you see here.... Martin

Nkuku, In the near future I have to make up some backing sand for use with lost foam work. I intend to do this from the perspective of someone just starting out in foundry work. Thus I will be doing it with minimum equipment and I have a few different ideas to make the process easier. So keep watching... Martin

internetmail. I seriously doubt that you can buy true facing sand anywhere. Years ago (many) you could buy what was know as "Old French Sand" I believe it came from a quarry somewhere near Paris. It was an extremely fine sand legendary for producing a fine finish but I seem to recall that the moulds had to be at least skin dried to keep problems associated with steam evolution from the very fine and therefore very low permeability sand at bay. There was an Americal equivalent (or at least close) called "Albany 00". Again it was a very fine sand even finer that the old french but the latter seems to have produced the better finished castings (I think). The AFS fineness number for Albany 00 ranged from 200 to 300 for the french around 175. Both were natural sands straight out of the ground )(like the sand I use). Clay levels were around 18 % and the sand was used at moisture levels of about 6%. these days sands for nonferrous work would typically have an AFS number of 70. They are synthetic sands i.e. made up from washed sands and bentonite clay. Old time foundries tended to use new sand as their facing material and "heap" or "floor" sand for the bulk of the mould. Heap and floor were just sand that had been used in the foundry. From this video of mine you can see that I do not buy my facing sand but rather I make it by grinding a mixture of used sand and new sand in a home made small flour style mill. This grinding process does produce a much finer sand but I have no idea of its AFS.. This is not a process that I would recommend as it does produce an very low permeability sand and that comes with a lot of problems that an occasional hobby caster might have trouble dealing with. Also the grinding is a slow messy and dangerous (silicosis - hazard) process..... Martin. PS if a fine finish is what you want maybe you should just buy some petrobond sand. Same brands of it are better than others but the good ones are very fine. You can use petrobond for part of a mould and normal green sand for the rest see here kzfaq.info/get/bejne/Y86capmB0JrFoZs.html this bloke is a brilliant moulder.

Dan, Yes, you are right I should wear a respirator as the dry sand is a silicosis hazard, and I often do but they are uncomfortable to wear and not the best of looks for a video. These two facts are hardly relevant I realize but what is relevant is than many respirators do not work that well and thus provide little protection particularly if they don't fit properly and most don't. In this case water gets added fairly quickly and once wet the sand is not a hazard. But you point is still taken as correct... Martin

I am 57 and did same not wearing one now I am paying for not using one we would rather have you healthy all dust is bad for you even with the bandit rag is beater than nothing you know like the cowboys did but its up too you I wont push ,I wish I knew half of what you know I enjoy your video's.

Dan, I do wear one most of the time. I just spent 4 days grinding up two 250 litre drums of sand to turn it into facing sand, it was hot dry weather and the work was dusty so uncomfortable though it was I did wear a respirator every time I went into the dust zone. I have in my life been exposed to asbestos and used to smoke heavily! Last time my lungs were checked they were Ok and the doctor commented that I was lucky. Sadly I am a little older than you, reverse your numbers and you would be close! But even so I hope to go on making videos for a while yet, touch wood! I am grateful for your concern and am glad that you enjoy my videos, Thanks.... Martin

take care martin god loves you and always has ,and most people watching you do too.

Hey Martin, glad to see the warning about the dust at the beginning of you vid. In my many jobs I held the only one that held a hidden danger was being a master tile setter. I became aware of it after about 15 years. Free silica sand is so fine you can see it glitter in the light. It's in basically every product that has Portland cement in it. Still can't believe your age, I'm not much younger than you and your moving better than a lot of 30 sumthins I've seen. Good info still trying to see all your vids.

Gerald, Your building? Mine was fine. Seriously though, since then I have got a wireless mic system and the sound quality has improved greatly... Martin

I meant the screen transition looked your like wall folded in

Gerald, Ah, I see it all! Some of these transitions seem to come on a bit sudden. They don't seem to take up their own space rather they seem to overwrite an existing part of the video. But this one sure was a bit "the building is falling down" sudden. I will keep working on it in future videos and see if I can do a little better. Thank you for clarifying.. Martin

Gerald, I have done some experimenting and it seems the transitions look a bit better if they are over a greater time and thus they do not appear quite a sudden. The only problem with this is that they overwrite more of the actual video. To leave enough time immediately before a transition so the overwrite is not a problem is not always as easy as one might imagine... Martin

Now here you have got me! I have never tried a cement mixer as a sand conditioning device. Perhaps there is someone out there who has done so and can tell us how well it worked. Mullers work by smearing the clay over the sand grain surface and general mixing /lump breaking up, but do tend to compact the sand so really needs aeration after mulling. My aerator sort of shears the sand whilst breaking up and lumps and thoroughly mixing the sand, don't know how well it spreads the clay though. I can see that a cement mixer would break up an lumps and mix the sand well but I am not sure that it would spread the clay over the sand grains as effectively as a muller and I do not know how well it would aerate the sand. However it is an interesting idea - potentially a cheap easy solution to sand preparation so, I repeat, if anyone out there has tried it let us know how it went.

Might I suggest a mason's mixer instead? A cement mixer is usually an open ended barrel with fins much like a clothes dryer that rotates and folds over the mix. This open design is needed so that there is nothing that the large aggregate can jam or wedge into. A masonry mixer is a tub with a shaft running through it lengthwise studded with paddles and doctor blades to scrape the sides spaced 180 degrees. While I have one, my sand needs are in the area of two 5 gal buckets so I haven't tried old Bertha (She's one of the bigger models). I don't see why swapping the doctor blades on one side with wedge type paddles or maybe even rubber snow blower paddles wouldn't work. That way the sand would get smeared during 1 pass then mixed/aerated during the next. I see the older units like mine in scrap yards on occasion.

Eddie, You may well be onto something here - what you are describing sounds something like what many call a "Z mixer" where blades push the material first one way and then the other. I have seen these use in foundries to great effect to mix silicate sands and also the older type of oil bonded core sands. Certainly smearing then mixing then aerating is the go - Must say though that I have great faith in my little aerator its a quick easy build and the sand feels so nice (sort of smooth and silky) after its been through this machine.

I was in no way belittling your aerator, Sir. I was merely suggesting that a masonry mixer would be a better alternative to a cement mixer for sand conditioning. As a person that lives in a city that was formerly an industrial powerhouse in a country that has access to just about anything - it baffles and aggravates me to no end that I cannot obtain anything foundry related in hobby quantities or prices if at all. No oil sand, no proper bentonite, no refractories. I am stuck with course sand and grinding cat litter. Perhaps a sand mill along the lines of yours will be built soon for my shop. I was looking at your de-gasser and I think that a stationary unit may not provide small enough bubbles due to the higher density of liquid aluminum forcing the gas to collect into a large enough bubble to break free and rise. Rotation or agitation should break a bubble free of the orifice before it would do so naturally. I am also wondering how something like a porous aquarium bubbling stone might work. As for a coating to protect the contraption, I wonder if graphite mixed into sodium silicate (both of which I have on hand) would suffice. So much to think about while awaiting good weather to return...

Eddie, My dear Sir, I took no offence and nor did my aerator :) I think that you are right it would be a good alternative - Perhaps someone out there has tried one and could let us know how they got on.Sounds like Detroit! No wonder you are grouchy :) If you think its bad over there come out here, our manufacturing industry is absolutely non existent. But I can at least get most of the supplies that you mention, not always in hobby quantities that's for sure but perhaps if a few of you get together you can share the commercial quantities out - got to be other foundry types near you. Also you could try approaching a small commercial foundry if you have one nearby and asking them if they will sell you small quantities of what they regularly use, expect to pay a bit of a premium at least in beer most foundry men love the odd beer now and again (and again and again.) Re cat litter why not turn it into a slurry with water and mixing that with the sand rather than trying to grind it up first. Re degasser I am not sure if density would make any difference I will have to think on that. Initial thoughts are that the greater metal density may mean that a bubble would rise sooner in metal as the up thrust on the bubble would be greater thus they may actually start out smaller in metal but as they rise and the pressure backs off they will obviously become bigger - I need to think more on this. The RID units do rely on rotation - basically a pump impellor that pulls in the molten aluminium injects the purge gas into it and spits the metal gas mixture out all through the treatment crucible. I believe bubble size is around 1 mm or below and they will successfully degas in around 5 minutes. Porous plug lances are available (just like a big aquarium stone) some a graphite tube with a piece of porous brick glued on the end, others are like a silicon carbide "hocky stick" with the bottom bit made out of porous silicon carbide. Generally it is reckoned that porous plug devices need about 15 or 20 minutes to satisfactorily degas (makes my 7 minutes a bit sus!) Many foundries use these devices. Many use a RID then deliver the metal to the holding pots that have a porous plug degasser running continuously in them (this is typical in gravity die work) I have noticed that these porous plug devices are quite variable in their bubble size even from unit to unit of the same type from the same supplier. Re coatings, the boron nitride that I use (an American product) is the best I have ever come across but it is very expensive. But you could certainly try a graphite and sod silicate mix it will be way, way better than nothing - you could even add a little bentonite (opps, sorry - kitty litter :)) to the mix as suspending agent. I am waiting for the good weather to return too - for foundry work winter is the good weather mind you our winters are mild compared to some of yours lowest we ever get is 8 Deg C and usually not below 11 deg C

JB, Where abouts in OZ - I am in Melbourne. Yes, I had noticed that some "corn flour' - and its called corn flour on the packet - actually states on the packet "made from wheat" - Buggered if I know how they do that! I always look to see that its made out of "maize". I have a pattern maker friend who is going to deliver me some wood flour as the last foundry supply house that sold it has changed hands and the new people "rationalized" some lines right out of existence. I think the wood flour would be the better as in an upcoming video I increased the corn flour to 1% and I was not happy all that with the surface finish - I would like to see what wood flour can do.

I'm located in Perth mate, one of my next projects is building up an electric kiln/furnace for aluminium casting (lost PLA 3d printing or wood/sandcast parts) very early days yet, and I am really enjoying your videos, extremely useful information from someone who i'm sure has forgotten more than I will ever know about the subject :-)

JB, Yeh, I sorta figured that it may have been WA, all that red soil sort of gave it away. I have not done any lost PLA (or foam for that matter) but from what I know of the process most people do not take full advantage of its abilities. My understanding is that you coat the to be lost pattern with a thin refractory wash. (I have experimented with this and a 50:50 mix of bentonite clay and talc mixed with enough water to make a slurry can be painted on the pattern or the pattern can be dipped) When the wash is dry the pattern is immersed in dry binderless sand usually with the aid of a bit of vibration and the casting then poured. To me it makes little sense to have to ram a typical green sand around a to be lost pattern - may as well be a pattern that you pull out, but the binderless sand technique has a lot to offer. I have an article or two on this, if you want a copy contact me privately. I have used a 3D print as a normal pattern - unfortunately they do not make very good patterns as the finish just isn't there - I had to do a fair bit of work with automotive spray putty and sand paper to get it good enough and then it was a bit weak to withstand the rapping bar being used but of course you can print it solid in areas where you need it stronger. I am glad that you are enjoying the videos and particularly glad that you are finding them useful. You will be surprised just how quickly you pick up knowledge when you get involved - in a few years it could easily be you giving out the useful stuff.

very keen for any information on lost PLA. this is probably more similar to lost wax as a technique, with plaster investment and burnout prior to pour, instead of foam dissolving as the metal is poured through. My thoughts here are as you suggest, surface finish can be quite rough on 3d prints, resisting clean pattern removal, especially with the fine facing sand you have there. I have experimented with some smoothing techniques for 3D prints, using acetone vapour with ABS plastic as per www.flickr.com/photos/87180506@N08/14685025020/in/album-72157646305370541/ very much smoother and quite a quick process ( a few minutes if that) I will contact you separately thank you!

JB, Had a look at those flickr photos - it sure seems to do at least a fair bit of the smoothing and therefore greatly cut down what needs to be hand done. I await you separate contact.